Effect of CS1 in Subjects With Pulmonary Arterial Hypertension

CS1 delayed-release capsules will be supplied with 160 mg active pharmaceutical ingredient (sodium valproate) per capsule. Three dose levels that will be evaluated in this study; study drug will be administered as uneven, divided doses twice daily in the morning and in the evening (1/3 of the daily dose is to be administered between 7 and 9 am; 2/3 of the daily dose is to be administered between 7 and 9 pm).